Microtubules are hollow polymers made up of tubulin subunits. Neurons, like other eukaryotic cells, contain a pool of free tubulin subunits and a pool of the microtubule polymers. These two pools dynamically exchange with one another such that microtubules undergo bouts of assembly and disassembly.n neurons, microtubules are also nucleated at the centrosome (located in the cell body of the neuron), but the microtubules are then severed from the centrosome so that they can be deployed into axons and dendrites.
If the parent makes this election, the child does not have to file a return. Earned and Unearned Income. If a child has both earned and unearned income, he or she must file a return (2016 and 2015) if: unearned income was over $1,050; earned income was over $6,300, or
-- $20,900 for married couples filing jointly in which both spouses are 65 or older. If you are married filing separately, you must file a tax return if your income is $3,650 or more, regardless of your age.Dependent children who worked for wages or tips or who collected income from investments in 2009 must file a tax return if: -- their earned income from a job was at least $5,700.f youâre 65 or older, the filing thresholds are higher: -- $10,750 for single filers. -- $13,400 for heads of household. -- $16,150 if you were widowed in 2007 or 2008 and have a dependent child. -- $19,800 for married couples filing jointly in which one spouse is 65 or older.